Arteriosclerotic diseases of the coronary vessels are the most frequent cause of death in the industrialized nations. A widespread cause of a coronary infarction is narrowing of the coronary vessels, so-called stenoses, or lipid-filled so-called “vulnerable plaques”.
To treat such conditions a so-called stent, a vessel support which as a rule consists of a wire mesh, is inserted into the stenotized vessel as part of an interventional cardiological measure.
If such a stent is to be positioned in non-critical areas of the blood vessel system this can basically be done without any major problems.
However this situation is different if a stent is to be placed in the vicinity of an ostium or a bifurcation. In such cases the stent must be placed very exactly, in some cases down to within one millimeter.
The problem with such placement however is that the blood vessel system of the coronaries moves with the movement of the heart. The catheter thus moves to a significant extent through the deformation of the heart vessels which occurs when the heart moves, with the speed of movement depending on the heart phase so that it can occur at a lower or a higher speed.
If the placement of a stent in critical vessel areas, i.e. in the vicinity of bifurcations for example, is not exact, the risk of an earlier thrombosis formation then increases possibly with a subsequent embolization. Furthermore restenosis can occur because of turbulences around an imprecisely placed free stent end.
The displacement of a catheter in the vessel which can arise as a result of the periodic movement of the heart can be within the range of up to 6 mm, so that the danger of an inexactly positioned stent can arise here with the associated risks described above.